Understanding Gum Line Cavities
Gum line cavities are a type of tooth decay that forms where the tooth meets the gums. These cavities are sometimes referred to as root caries or cervical caries due to their location.
The tooth structure at the gum line differs from chewing surfaces. Above the gum line, enamel, the hardest substance in the human body, covers the tooth. Below or at the gum line, especially if gums have receded, the softer root surface (cementum and dentin) becomes exposed. This difference in hardness makes this area vulnerable to decay.
Primary Drivers of Gum Line Cavities
The primary cause of gum line cavities is bacteria in dental plaque. Plaque is a sticky, colorless film of bacteria that constantly forms on teeth, especially along the gum line. These bacteria consume sugars and carbohydrates from the foods and drinks we consume.
As bacteria metabolize sugars, they produce acids. These acids attack the tooth surface, initiating demineralization. At the gum line, where the softer cementum and dentin are often exposed, this demineralization occurs more rapidly than it would on enamel. The acid dissolves the tooth’s mineral content, forming a cavity.
If not removed regularly through brushing and flossing, plaque accumulates, and the acidic environment persists. This sustained acid attack progressively erodes the tooth structure. Over time, this localized acid exposure results in a cavity.
Factors That Increase Vulnerability
Several factors increase susceptibility to gum line cavities, often by exposing the root surface or altering the mouth’s protective mechanisms. Gum recession, also known as gingival recession, is one factor, occurring when gum tissue pulls back and exposes the previously protected root surface.
Aggressive tooth brushing also contributes. Brushing too hard, especially with a stiff-bristled toothbrush, wears away gum tissue and the softer tooth structure at the gum line. This mechanical abrasion exposes the dentin and cementum, making them more susceptible to acid attacks from plaque.
Acid erosion from diet or acid reflux can further compromise tooth structure. Frequent consumption of acidic foods and beverages, such as citrus fruits, sodas, and sports drinks, can soften the tooth surface, particularly the exposed root. Similarly, stomach acid from reflux can bathe the teeth in acid, increasing the risk of demineralization at the gum line.
Dry mouth (xerostomia) reduces the mouth’s natural defenses. Saliva plays a role in washing away food particles, neutralizing acids, and remineralizing early lesions. When saliva flow is reduced, often due to medications, medical conditions, or aging, the protective effects are diminished, leaving the teeth more vulnerable to decay.
Abfraction, or V-shaped lesions at the gum line from excessive biting forces or teeth grinding, is another factor. While not a direct cause of decay, these lesions create areas where plaque accumulates more easily. The compromised tooth structure then becomes more prone to cavity formation.